Sewing machine driving devices



June 10, 1958 A. H. ERIKSSON 2,838,020

SEWING MACHINE DRIVING DEVICES Filed June 8, 1954 y 2 Sheets-Sheet l lli I June 10, 1958 H, 0N 2,838,920

SEWING MACHINE DRIVING DEVICES Filed June 8, 1954 2 Sheets-Sheet 2,

I 25 I a I United States Patent 2,838,020 SEWING MACHINE DRIVING DEVICES Allan Herman Eriksson, Huskvarna, Sweden, assignor to Husqvarna Vapenfabriks Aktiebolag, Huskvarna, Sweden, a corporation of Sweden Application June 8, 1954, Serial No. 435,274 6 Claims. (Cl. 112-420) ber and comprises two mutually. coaxial gear wheels for engagement with two corresponding counterwheels fixed to the driving member and the driven member, respectively. The driving member is preferably provided at one end with a coaxial pin reaching outside of the casing and adapted, upon rotation, to bring with it a thread-spool slid on to the pin which is provided with a coupling part adapted to be actuated by the spool when being slid on to the pin, so as to release the driven member from the driving member. The invention provides for an easilyoperated, simple and reliable driving device whereby the sewing machine may be driven at low speed suitable for darning and embroidering, for instance. After disconnecting the driven member and, consequently, the sewing machine, spooling of thread may be performed to advantage, particularly if the driving member is driven at a relatively low speed of rotation about a fixed axis. Preferably, the driving member should be driven from a rotary shaft such as that of an electric motor, by means of a speed-reducing-transmission instead of being mounted on such shaft.

The invention will be more closely described in the following With reference to the annexed drawings wherein:

Fig. l is an end-view of a sewing machine provided with a driving device according to the invention,

Fig. 2 is a partial front view of the machine, partly in section,

Fig. 3 is a section on line III-III in Fig; l

Fig. 4 is an enlarged vertical section through the driving device on line IVIV in Fig. 3,

Fig. 5 is a section on line V.-V in Fig. 4,

Fig. 6 is a section corresponding to Fig. 4, through a modified part of the driving device in Fig. 4.

The drawings illustrate an application of the invention to a portable, electrically driven domestic sewing machine, the hollow frame or casing of which comprises a base plate 1, a standard 2 having a cantilevered arm 3 for a needle head and a lower work supporting arm not shown, a motor-housing 4, and a detachable end-wall 5 of this housing and a lower part of the standard which end-wall is omitted in Fig l. The arm 3 contains the main drive-shaft 6 of the machine which shaft is provided with a belt pulley 7 and a balance wheel 8.

The driving device of the machine shown comprises an electric motor 9 positioned in the housing 4 and the shaft 10 of which is parallel to the shaft6 and provided with a belt pulley 11 for a belt 12 disposed inside the end-wall 5 and also running over a considerably larger r 2,838,020 Ce Patented June 10, 1958 belt pulley 13 provided with a gear wheel 14 and rigidly secured to a sleeve 16 which is rotatably but not slidably mounted on a cantilevered stub shaft 24 parallel to the shaft 6. Rotatably but not slidably mounted on the sleeve 16 is a belt pulley 21 provided with a gear wheel 22 and connected to the belt pulley 7 by means of a belt 40 disposed in the standard 2. A part 41 fixedly mounted in the belt pulley 13 is provided with a pin 18 which is coaxial to the pulley and extends outside of the end-wall 5, and the diameter of which corresponds to the inner diameter of a spool 42 for under-thread which spool may be of known design. The belt pulleys 13 and 21 are interconnectible by means of a coupling which, in the embodiment shown comprises an axial key 19 mounted in grooves 15, 17 in the belt pulley 13 and the sleeve 16, respectively, and in a corresponding groove in the part 41. The key is pivotally mounted at one end on a pin 43 mounted in the part 18 and is adapted with its opposite, free end to engage in either of two opposite recesses 23 in the belt pulley 21 under the pressure of a spring mounted in the part 41. In this operative position, indicated by full lines in Fig. 4, the key reaches somewhat beyond the circumference of the pin 18.

In the embodiment shown the reduction gear comprises a pair of rigidly interconnected spur wheels 30, 31 which are rotatably mounted on a cantilevered stub shaft 32 parallel to the shaft 24, and are axially displaceable into and out of engagement with the spur wheels 14 and 22, respectively' The wheels 30, 31 are preferably formed integral with one another and of a plastic, such as Bakelite or nylon. The shaft 32 has two shoulders 33, 44 and reaches outside of the end-Wall 5 with a threaded part 34 upon which an operating member 35 may be screwed so as to abut against the shoulder 44 with a sleeve-shaped part 36 the inner diameter of which preferably corresponds to the diameter of the pin 18. In their inoperative position shown in Fig. 4 the gear wheels 30, 31 engage the operating member under the pressure of a helical spring 37 surrounding the shaft 32 and engaging the gear wheels by means of a washer 38 adapted to engage the shoulder 33 on the shaft in the operative or meshing position of the gear wheels.

The shafts 24, 32 are preferably mounted on a common frame part adjustable in the transverse direction of the shafts. 1n the embodiment shown they are thus screwed to a plate having wide openings 26 for two screws 27 with Washers 28, by means of which the plate is screwed to a part rigidly mounted in the machine-casing, preferably a bracket 29 for the motor 9. Thereby the assembly of the driving device is facilitated and the tension of the belts 12, 14 may readily be adjusted.

In the position shown in Fig. 4 the belt pulleys are coupled together directly, the machine being driven at a relatively high speed which may be varied within certain limits by means, for instance, of a motor control rheostat known per se and not shown. When a spool 42 is to be spooled with thread, it is slid on to the pin 18, thereby operating the key 19 so that the latter, against the action of spring 20, is depressed into its inoperative position indicated by dash-and-dot lines whereby the belt pulley 21, and consequently also the shaft 6 will be disconnected from the motor. By friction the spool is thereupon caused to partake in the rotation of the belt pulley 13 which rotation, due to the speed-reducing belt transmission 11-13, takes place at a speed suitable for spooling, although the motor is disconnected from the sewing machine. During the spooling operation thread may be conducted to the spool by members arranged on the machine frame, such members being known per se and not shown. After the spooling operation the spool is pulled off from the pin 18 whereby the key 19 is re- 3 leased and rapidly snaps into either of the grooves 23. When the machine is 'to 'be driven at low speed, during darning, for instance, the operating member 35 is unscrewed from the shaft 32 and is instead slid on to the pin "18. Thereby the gear wheels '39, 31 are brought into engagement with the gear wheels 14, 22 and the coupling 'key 19 is disengaged from the belt pulley 21. By the spur gearings 14, 3t and 31, 22 the speed of the arm-shaft 6 is thereby reduced to such a degree, in the ratio 4.5 to l, for instance, that it is possible to sew stitch by stitch with uniform speed and without the risk of motor stop. When the gear wheels 30, 31 are in engagement, the pressure of the spring 37 is borne by the shoulder 33 on the shaft 32 and notby said wheels. A return to normal speed can readily be accomplished by pulling off the operating member 35 from the pin 13 and again screwing it on to the shaft 32. This and other setting of the .driving device in Fig. 4 is generally performed while the motor is at a standstill. If it is performed while the machine is running, it happens that the belt "12 will slip temporarily.

Fig. 6 shows a modified embodiment of the reduction gear and its operating member. Here the shaft 32 is substituted by a shorter shaft 56, at its free end provided with a flange 51,,pre'ferably in the shape of a screw head. The gear wheels 30, 31 correspond to a pair of sliding-wheels 52, 53 adapted, in their inoperative position shown, to abut against the plate 25 with a hub portion 54, and in the operative position to abut against the flange 51 under the pressure of a spring, not shown, surrounding the hub portion. The operating member is constituted by a set-screw 55 mounted in the end-wall 5 and provided with a grip 56 outside the end-wall. Inside the end-wall the set screw has a stop-flange 57 and a pin 58 adapted to abut against the gear wheel 52 and keep it in inoperative position. The operating member may be unscrewed until the flange 57 abuts against the endwall, the sliding-wheels occupying the above-mentioned operative or meshing position. Here the operating mem- -ber is not easily detachable and adapted to be slid on to a pin on the driving member (1316) for disconnecting the driven member (21, 22). Such disconnection may instead be accomplished for instance by sliding on to the pin in question one of the spools (42) of the machine.

Also various other embodiments are evidently possible within the scope of the invention. The latter may thus be applied to advantage also in sewing machines the main drive-shaft of which is arranged, not in an upper frame arm but in a lower work-carrying arm or below a workcarrying base-plate. and axially slidable spur wheels the gear wheels of the drivingdevice may also be-constituted by friction wheels known per se. The driving member may, possibly, be mounted on the motor shaft or an extension thereof, although .thedriving member in such case obtains a speed unsuitably high for thread spooling purpose. It may finally be noted that the invention is of importance also in sewing machines with .a treadle driving device. In the embodiment shown either of the belt pulleys 11 and 13 might thus be belt-driven from the flywheel of a treadle driving device known per se.

I claim:

1. In a sewing machine having a casing and a main drive shaft 'rotatably mounted therein; driving means for said main .drive shaft disposed within said casing and comprising in combination a power .driven shaft, a rotary driving member driven by said power driven shaft and provided with a coaxial pin extending outwardly of the casing for rotating a thread spool upon being slid thereon, a rotary driven member coaxially of said driving member and being operatively connected to said main drive shaft, said pin being provided with an axial groove opening through the periphery thereof, and said rotary driven member being provided with a recess, an elongated coupling member pivotally connected to said driving member,

Instead of consisting of mutually spring means supported by said driving member normally urging an end portion of said coupling member into said said cluster gear wheels normally out of driving engagement with said first mentioned gear wheels, and means accessible externally of said casing for effecting driving engagement of the said first mentioned and said cluster gear wheels for the purpose set forth.

'2. The structure according to claim 1, wherein said reduction cluster gear is supported for rotation and for axial movement on a fixed shaft supported in said casing, a helical spring encircling said shaft and bearing on one side of said cluster gear for biasing said cluster gear wheels toward driving engagement with said first mentioned gear wheels, and said ,last mentioned means normally engaging the opposite side of said cluster gear for retaining said first and second gear wheels out of driving engagement.

3. In a sewing machine having a casing and a main drive shaft rotatably mounted therein, driving means in said casing for said main drive shaft, comprising in combination, an electric motor having a primary drive shaft, a rotary driving member provided with a co-axial pin projecting outwardly of the casing and adapted upon rotation to rotate a thread spool upon being slid onto the pin, a belt transmission between said primary drive shaft and said driving member, a rotatable driven member coaxial with said driving member and having a drive connection with said main drive shaft, said pin being provided with a radial groove, a recess in said driven member, an elongated coupling member disposed in said groove and having one end thereof pivotally connected to said pin, a spring supported by said pin and bearing on said coupling member for normally urging the opposite end thereof into said recess, a reduction cluster gear disposed in said casing and comprising a pair of rigidly interconnected spur wheels, a corresponding pair of counter wheels fixed to the driving and driven members respectively, said cluster gear being mounted in the casing on an axis parallel to the axis of said driving and driven members for axial movement into and out of driving engagement between said spur wheels of said counter wheels, means normally biasing said spur wheels into driving engagement with said counter wheels, and manually operable means accessible externally of the casing normally restraining said biasing means, and providing for operation thereof for engagement of the spur wheels with the counter wheels.

4. 'The structure according to claim 3, wherein said coupling member when engaged with said recess has the pivoted end portion thereof extending redially outwardly of said groove whereby upon application of said thread spool to said pin said coupling member is withdrawn from said recess with a resulting disconnected drive between said driving member and said driven member.

5. The structure according to claim 1, wherein said driving :member and said driven member are rotatable about a stub shaft, said cluster gear being rotatable about a second stub shaft parallel with said first mentioned stub shaft, and said stub shafts having corresponding ends thereof supported by a frame member disposed within said casing, said frame member being adjustable transversely of ithe shafts.

.6. The structure according to claim 1, wherein said cluster gear supporting means comprises a stub shaft 5 6 having one end thereof secured to a frame member dis- References Cited in the file of this patent posed within said casing, a coil spring encircling said UNITED STATES PATENTS stub shaft with its opposite ends reacting on said frame member and the adjacent end of said cluster gear, and 1,236,225 Stanton 1917 said last mentioned means comprising a member adjust- 5 2'173286 Robe SePt- 1939 able axially of said stub shaft and bearing on the opposite FOREIGN PATENTS end of said cluster gear for selectively holdingsaid spring 642,536 Germany Man 8, 1937 in lneffective compressed condition and permitting same 621,431 Great Britain 8 1949 to expand and move the cluster gear in driving engagement with said first mentioned gear wheels. 10 

